Early Repolarization: Maybe Not So Benign After All
A retrospective evaluation shows that patients with sudden cardiac arrest without demonstrable heart disease often have electrocardiographic findings of early repolarization.
Experimental evidence suggests that early repolarization is associated with ventricular dysrhythmias, but no clinical evidence is available. In a case-control study, researchers reviewed data from 22 dysrhythmia centers in several countries to evaluate the prevalence of early repolarization and its association with dysrhythmia in patients younger than 60 who had idiopathic (no evidence of structural heart disease) sudden cardiac arrest and had received implantable defibrillators.
The researchers identified 206 cases (60% men; median age, 36) and compared them with 412 matched controls who had not had cardiac arrest and did not have evidence of heart disease. Early repolarization (defined as a J-point elevation >/= 1 mm) was significantly more frequent in the cardiac-arrest group than in the control group (31% vs. 5%) and, when present, was significantly greater in magnitude in the cardiac-arrest group (2.0 vs. 1.2 mm). Nearly 30% of patients in the cardiac-arrest group had a history of syncope. Defibrillator interrogation (in 18 patients) showed that dysrhythmias were preceded by an increase in J-point elevation. In the one third of cardiac-arrest patients who had early repolarization and had pre-arrest electrocardiograms available, the pre-arrest ECGs showed early repolarization. During a mean follow-up of 61 months, the three patients with the highest J-point elevation (>5 mm) together had more than 50 episodes of ventricular fibrillation (VF), resulting in the death of one patient. Few patients in the cardiac-arrest group were athletes or blacks, groups in which repolarization abnormality is most common.
An editorialist notes that while repolarization abnormality is common, sudden cardiac arrest is not, and that patients with the characteristic ECG findings who are symptomatic (i.e., syncope, palpitations, chest pain) require close monitoring, with particular attention to intermittent increases in J-point elevation.
Comment: Although ventricular fibrillation is uncommon in young people, this study suggests that we make two important changes in our approach to "benign" early repolarization. First, an ECG that shows early repolarization should not be considered as normal in patients who have had syncope or symptoms of dysrhythmia. Second, patients undergoing electrocardiography in the emergency department for unrelated reasons who have findings of early repolarization abnormality should be told about the symptoms of dysrhythmia and advised to seek care if these symptoms should arise.
J. Stephen Bohan, MD, MS, FACP, FACEP
Published in Journal Watch Emergency Medicine May 30, 2008
Citation(s): Haïssaguerre M et al. Sudden cardiac arrest associated with early repolarization. N Engl J Med 2008 May 8; 358:2016.